Check external IDs used in AEs

[mcourtot]

eg, for Ahi1 Q8K3E5, we have AEs using CL:0000002, which is deprecated. Possible checks include:

• checking label: most OBO resources would update label to "obsolete X" when X is deprecated. Though this is not a policy, but only usage.
• checking the hierarchy: should be coordinated with OLS as our info comes from there.